Apparatuses and methods for folding absorbent articles

ABSTRACT

The present disclosure relates to folding methods and apparatuses that operate to fold an advancing substrate in the cross direction along a central region to bring a second end region into a facing relationship with a first end region. In some embodiments, the second end region of the advancing substrate is folded around a folding axis 180° to bring the second end region into a facing relationship with the first end region. The folding axis may also be defined by an arc extending in the machine direction MD, wherein the second end region of the advancing substrate is helically folded toward the inside of the arc. A folding apparatus including a curved or arc-shaped folding axis may also be configured such the first and second web paths have substantially equal lengths.

FIELD OF THE INVENTION

The present disclosure relates to methods for manufacturing absorbentarticles, and more particularly, to apparatuses and methods for foldinga continuous length of absorbent articles.

BACKGROUND OF THE INVENTION

Along an assembly line, various types of articles, such as for example,diapers and other absorbent articles, may be assembled by addingcomponents to and/or otherwise modifying an advancing, continuous web ofmaterial. For example, in some processes, advancing webs of material arecombined with other advancing webs of material. In other examples,individual components created from advancing webs of material arecombined with advancing webs of material, which in turn, are thencombined with other advancing webs of material. In some cases,individual components created from advancing web or webs are combinedwith other individual components created from other advancing web orwebs. Webs of material and component parts used to manufacture diapersmay include: backsheets, topsheets, leg cuffs, waist bands, absorbentcore components, front and/or back ears, fastening components, andvarious types of elastic webs and components such as leg elastics,barrier leg cuff elastics, stretch side panels, and waist elastics. Oncethe desired component parts are assembled, the advancing web(s) andcomponent parts are subjected to a final knife cut to separate theweb(s) into discrete diapers or other absorbent articles.

In some converting configurations, discrete chassis spaced apart fromeach other are advanced in a machine direction and are arranged with alongitudinal axis parallel with the cross direction. Opposing waistregions of discrete chasses are then connected with continuous lengthsof elastically extendable front and back belt webs advancing in themachine direction. While connected with the chassis, the front and backbelt webs are maintained in a fully stretched condition along themachine direction, forming a continuous length of absorbent articles.The continuous length of absorbent articles may then be folded in across direction. During the folding process in some convertingconfigurations, one of the front and back belt webs is folded 180° intoa facing relationship with the opposing belt. However, the web pathlength of one of the belt webs may be longer than the opposing belt web.Such differing web path lengths may create problems associated withbringing the belt webs together in a desired alignment.

Consequently, it would be beneficial to provide a method and apparatusfor folding a continuous length of absorbent articles that provides areduction in mismatched web travel paths during the production process.

SUMMARY OF THE INVENTION

The present disclosure relates to folding methods and apparatuses thatoperate to fold an advancing substrate in the cross direction along acentral region to bring a second end region into a facing relationshipwith a first end region. In some embodiments, the second end region ofthe advancing substrate is folded around a folding axis 180° to bringthe second end region into a facing relationship with the first endregion. The folding axis may also be defined by an arc extending in themachine direction MD, wherein the second end region of the advancingsubstrate is helically folded toward the inside of the arc. A foldingapparatus including a curved or arc-shaped folding axis may also beconfigured such the first and second web paths have substantially equallengths.

In one form, an apparatus may be configured for folding a continuouslength of absorbent articles comprising a plurality of intermittentlyspaced chassis advancing in a machine direction, each chassis having afirst end portion and an opposing second end portion separated from eachother in the cross direction by a central portion, and each chassishaving a first surface and an opposing second surface. The apparatusincludes: a conveyor adapted to advance the first end portions of thechassis in the machine direction; a plurality of rollers adapted toadvance the second end portions of the chassis in the machine direction,the plurality of rollers defining a web path that positions the secondsurface of the second end portion of the chassis into a facingrelationship with second surface of the first end portion of the chassisas the chassis advance in machine direction; wherein the plurality ofrollers are intermittently spaced along the machine direction, eachroller having a rotation axis, the rotation axis of each roller beingsubstantially perpendicular to a folding axis extending in the machinedirection, wherein the central portions of the chassis are folded aboutthe folding axis, and wherein the folding axis is curved.

In another form, a method may be configured for folding a continuouslength of absorbent articles comprising a plurality of intermittentlyspaced chassis advancing in a machine direction, each chassis having afirst end portion and an opposing second end portion separated from eachother in the cross direction by a central portion, and each chassishaving a first surface and an opposing second surface. The methodincludes the steps of: advancing the first end portions of the chassisin the machine direction; advancing the second end portions of thechassis in the machine direction along a web path that positions thesecond surface of the second end portion of the chassis into a facingrelationship with second surface of the first end portion of the chassisas the chassis advance in machine direction; and folding the centralportions of the chassis about a folding axis extending the machinedirection, wherein the folding axis is curved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a diaper pant.

FIG. 2A is a partially cut away plan view of the diaper pant shown inFIG. 1.

FIG. 2B is a partially cut away plan view of a second embodiment of adiaper pant.

FIG. 3A is a cross-sectional view of the diaper pants of FIGS. 2A and 2Btaken along line 3A-3A.

FIG. 3B is a cross-sectional view of the diaper pants of FIGS. 2A and 2Btaken along line 3B-3B.

FIG. 4 is a schematic side view of a converting apparatus adapted tomanufacture pre-fastened, pant diapers.

FIG. 5A is a view of a continuous length of chassis assemblies from FIG.4 taken along line A-A.

FIG. 5B1 is a view of a discrete chassis from FIG. 4 taken along lineB1-B1.

FIG. 5B2 is a view of a discrete chassis from FIG. 4 taken along lineB2-B2.

FIG. 5C is a view of continuous lengths of advancing front and back sidepanel material from FIG. 4 taken along line C-C.

FIG. 5D is a view of multiple discrete chassis spaced from each otheralong the machine direction MD and connected with each other by thefront and back side panel material from FIG. 4 taken along line D-D.

FIG. 5E is a view of folded multiple discrete chassis with the front andback side panel material in a facing relationship from FIG. 4 takenalong line E-E.

FIG. 5F is a view of two discrete absorbent articles advancing themachine direction MD from FIG. 4 taken along line F-F.

FIG. 6 is an isometric side view of a continuous length of absorbentarticles advancing in a machine direction MD along an embodiment of afolding apparatus.

FIG. 7 is an isometric side view of the continuous length of absorbentarticles of FIG. 6.

FIG. 8 is an isometric side view of the folding apparatus of FIG. 6.

FIG. 9 is an isometric side view of a plurality of rollers and foldingaxis of FIG. 8.

FIG. 10 is an isometric side view of a conveyor of FIG. 8.

FIG. 11 is an end view of the folding apparatus of FIG. 8 lookingdownstream in the machine direction.

FIG. 11a illustrates the angles between the axes of rotation of theplurality of rollers and the +y axis of the folding apparatus of FIG.11.

FIG. 12 is a side view of an embodiment of a folding axis.

FIG. 13 is an isometric side view of a second embodiment of a foldingapparatus.

DETAILED DESCRIPTION OF THE INVENTION

The following term explanations may be useful in understanding thepresent disclosure:

“Absorbent article” is used herein to refer to consumer products whoseprimary function is to absorb and retain soils and wastes. “Diaper” isused herein to refer to an absorbent article generally worn by infantsand incontinent persons about the lower torso. The term “disposable” isused herein to describe absorbent articles which generally are notintended to be laundered or otherwise restored or reused as an absorbentarticle (e.g., they are intended to be discarded after a single use andmay also be configured to be recycled, composted or otherwise disposedof in an environmentally compatible manner).

An “elastic,” “elastomer” or “elastomeric” refers to materialsexhibiting elastic properties, which include any material that uponapplication of a force to its relaxed, initial length can stretch orelongate to an elongated length more than 10% greater than its initiallength and will substantially recover back to about its initial lengthupon release of the applied force.

As used herein, the term “joined” encompasses configurations whereby anelement is directly secured to another element by affixing the elementdirectly to the other element, and configurations whereby an element isindirectly secured to another element by affixing the element tointermediate member(s) which in turn are affixed to the other element.

“Longitudinal” means a direction running substantially perpendicularfrom a waist edge to a longitudinally opposing waist edge of anabsorbent article when the article is in a flat out, uncontracted state,or from a waist edge to the bottom of the crotch, i.e. the fold line, ina bi-folded article. Directions within 45 degrees of the longitudinaldirection are considered to be “longitudinal.” “Lateral” refers to adirection running from a longitudinally extending side edge to alaterally opposing longitudinally extending side edge of an article andgenerally at a right angle to the longitudinal direction. Directionswithin 45 degrees of the lateral direction are considered to be“lateral.”

The term “substrate” is used herein to describe a material which isprimarily two-dimensional (i.e. in an XY plane) and whose thickness (ina Z direction) is relatively small (i.e. 1/10 or less) in comparison toits length (in an X direction) and width (in a Y direction).Non-limiting examples of substrates include a web, layer or layers orfibrous materials, nonwovens, films and foils such as polymeric films ormetallic foils. These materials may be used alone or may comprise two ormore layers laminated together. As such, a web is a substrate.

The term “nonwoven” refers herein to a material made from continuous(long) filaments (fibers) and/or discontinuous (short) filaments(fibers) by processes such as spunbonding, meltblowing, carding, and thelike. Nonwovens do not have a woven or knitted filament pattern.

The term “machine direction” (MD) is used herein to refer to thedirection of material flow through a process. In addition, relativeplacement and movement of material can be described as flowing in themachine direction through a process from upstream in the process todownstream in the process.

The term “cross direction” (CD) is used herein to refer to a directionthat is generally perpendicular to the machine direction.

The term “pant” (also referred to as “training pant”, “pre-closeddiaper”, “diaper pant”, “pant diaper”, and “pull-on diaper”) refersherein to disposable absorbent articles having a continuous perimeterwaist opening and continuous perimeter leg openings designed for infantor adult wearers. A pant can be configured with a continuous or closedwaist opening and at least one continuous, closed, leg opening prior tothe article being applied to the wearer. A pant can be preformed byvarious techniques including, but not limited to, joining togetherportions of the article using any refastenable and/or permanent closuremember (e.g., seams, heat bonds, pressure welds, adhesives, cohesivebonds, mechanical fasteners, etc.). A pant can be preformed anywherealong the circumference of the article in the waist region (e.g., sidefastened or seamed, front waist fastened or seamed, rear waist fastenedor seamed).

“Pre-fastened” refers herein to pant diapers manufactured and providedto consumers in a configuration wherein the front waist region and theback waist region are fastened or connected to each other as packaged,prior to being applied to the wearer. As such pant diapers may have acontinuous perimeter waist opening and continuous perimeter leg openingsdesigned for infant or adult wearers. As discussed in more detail below,a diaper pant can be preformed by various techniques including, but notlimited to, joining together portions of the diaper using refastenableand/or permanent closure members (e.g., seams, heat bonds, pressurewelds, adhesives, cohesive bonds, mechanical fasteners, etc.). Inaddition, pant diapers can be preformed anywhere along the circumferenceof the waist region (e.g., side fastened or connected, front waistfastened or connected, rear waist fastened or connected).

The present disclosure relates to methods and apparatuses for foldingsubstrates advancing in a machine direction. The substrates may have acontinuous length extending the machine direction MD and may have afirst end region and a second end region separated from each other alonga cross direction CD by a central region. The folding methods andapparatuses discussed herein operate to fold the advancing substrate inthe cross direction along the central region to bring the second endregion into a facing relationship with the first end region. The foldingapparatuses may include a folding axis about which the central region ofthe advancing substrate is folded. In some embodiments, the second endregion of the advancing substrate is folded around the folding axis 180°to bring the second end region into a facing relationship with the firstend region. As such, the first end region of the advancing substratetravels in the machine direction along a first web path during thefolding process while the second end region of the substrate travels inthe machine direction along a second web path defining a helical shape.The folding axis may also be defined by an arc extending in the machinedirection MD, wherein the second end region of the advancing substrateis helically folded toward the inside of the arc. As discussed in moredetail below, a folding apparatus including a curved or arc-shapedfolding axis may be configured such the first and second web paths havesubstantially equal lengths.

It is to be appreciated that the folding methods and apparatuses hereinmay be configured to fold various types of substrates, the methods andapparatuses herein are discussed below in the context of manufacturingabsorbent articles. In particular, the methods and apparatuses arediscussed in the context of folding advancing, continuous lengths ofabsorbent articles during production. As discussed below, an advancingcontinuous length of absorbent articles may include a plurality ofchassis connected with a continuous first belt substrate and acontinuous second belt substrate. The continuous first and second beltsubstrates may be separated from each other along a cross directionwhile advancing along a machine direction MD. Each chassis may extend inthe cross direction and may include opposing first and second endregions separated by a central region, wherein the first end regions areconnected with first belt substrate and the second end regions areconnected with the second belt substrate. The chassis may also be spacedfrom each other along the machine direction MD. The folding apparatusoperates to fold the chassis around the folding axis along the centralregions and to bring the second belt substrate and second end region ofthe chassis into a facing relationship with the first belt substrate andfirst end region of the chassis. In some embodiments, the second beltsubstrate and second end region of the chassis is folded 180° around thefolding axis to bring the second belt substrate and second end region ofthe chassis into a facing relationship with the first belt substrate andfirst end region of the chassis. As such, the first belt substrate andfirst end region of the chassis travel in the machine direction alongthe first web path during the folding process while the second beltsubstrate and the second end region of the chassis travel in the machinedirection along the second web path defining a helical shape. Thus, thesecond belt substrate and the second end region of the chassis arehelically folded toward the inside of the arc of a curved folding axis.Again, the first and second web paths may have substantially equallengths.

As discussed in more detail below, embodiments of the folding apparatusmay include a conveyor and a plurality of rollers. The conveyor may beconfigured to advance the first end region of the substrate (or thefirst belt substrate and first end region of the chassis), and therollers may be configured to advance the second end region of thesubstrate (or the second belt substrate and second end region of thechassis). The conveyor may define a portion of the first web path andthe plurality of rollers may define the second web path. Each roller mayhave different angular orientations relative to another to provide asubstantially helical shape to the second path along the machinedirection MD. In some embodiments, the rotation axis of a roller may beangularly offset relative to a preceding roller upstream in the machinedirection MD. As the second belt substrate and second waist regions ofthe chassis advance along the second web path, the relative angularpositions between the rollers cause the second belt material substrateand second waist regions of the chassis to twist while advancing in themachine direction MD, and at the same time, fold the chassis along thefolding axis to place the second belt substrate into a facingrelationship with the first belt substrate.

As previously mentioned, the processes and apparatuses discussed hereinmay be used to fold various types of substrate configurations, some ofwhich may be used in the manufacture of different types of absorbentarticles. To help provide additional context to the subsequentdiscussion of the process embodiments, the following provides a generaldescription of absorbent articles in the form of diapers that includecomponents that may be folded in accordance with the methods andapparatuses disclosed herein.

FIGS. 1 and 2A show an example of a diaper pant 100 that may beassembled and folded in accordance with the apparatuses and methodsdisclosed herein. In particular, FIG. 1 shows a perspective view of adiaper pant 100 in a pre-fastened configuration, and FIG. 2A shows aplan view of the diaper pant 100 with the portion of the diaper thatfaces away from a wearer oriented towards the viewer. The diaper pant100 shown in FIGS. 1 and 2A includes a chassis 102 and a ring-likeelastic belt 104. As discussed below in more detail, a first elasticbelt 106 and a second elastic belt 108 are connected together to formthe ring-like elastic belt 104.

With continued reference to FIG. 2A, the chassis 102 includes a firstwaist region 116, a second waist region 118, and a crotch region 120disposed intermediate the first and second waist regions. The firstwaist region 116 may be configured as a front waist region, and thesecond waist region 118 may be configured as back waist region. In someembodiments, the length of each of the front waist region, back waistregion, and crotch region may be ⅓ of the length of the absorbentarticle 100. The diaper 100 may also include a laterally extending frontwaist edge 121 in the front waist region 116 and a longitudinallyopposing and laterally extending back waist edge 122 in the back waistregion 118. To provide a frame of reference for the present discussion,the diaper 100 and chassis 102 of FIG. 2A is shown with a longitudinalaxis 124 and a lateral axis 126. In some embodiments, the longitudinalaxis 124 may extend through the front waist edge 121 and through theback waist edge 122. And the lateral axis 126 may extend through a firstlongitudinal or right side edge 128 and through a midpoint of a secondlongitudinal or left side edge 130 of the chassis 102.

As shown in FIGS. 1 and 2A, the diaper pant 100 may include an inner,body facing surface 132, and an outer, garment facing surface 134. Thechassis 102 may include a backsheet 136 and a topsheet 138. The chassis102 may also include an absorbent assembly 140 including an absorbentcore 142 may be disposed between a portion of the topsheet 138 and thebacksheet 136. As discussed in more detail below, the diaper 100 mayalso include other features, such as leg elastics and/or leg cuffs toenhance the fit around the legs of the wearer.

As shown in FIG. 2A, the periphery of the chassis 102 may be defined bythe first longitudinal side edge 128, a second longitudinal side edge130; a first laterally extending end edge 144 disposed in the firstwaist region 116; and a second laterally extending end edge 146 disposedin the second waist region 118. Both side edges 128 and 130 extendlongitudinally between the first end edge 144 and the second end edge146. As shown in FIG. 2A, the laterally extending end edges 144 and 146are located longitudinally inward from the laterally extending frontwaist edge 121 in the front waist region 116 and the laterally extendingback waist edge 122 in the back waist region 118. When the diaper pant100 is worn on the lower torso of a wearer, the front waist edge 120 andthe back waist edge 122 of the chassis 102 may encircle a portion of thewaist of the wearer. At the same time, the chassis side edges 128 and130 may encircle at least a portion of the legs of the wearer. And thecrotch region 119 may be generally positioned between the legs of thewearer with the absorbent core 142 extending from the front waist region116 through the crotch region 119 to the back waist region 118.

It is to also be appreciated that a portion or the whole of the diaper100 may also be made laterally extensible. The additional extensibilitymay help allow the diaper 100 to conform to the body of a wearer duringmovement by the wearer. The additional extensibility may also help, forexample, allow the user of the diaper 100 including a chassis 102 havinga particular size before extension to extend the front waist region 116,the back waist region 118, or both waist regions of the diaper 100and/or chassis 102 to provide additional body coverage for wearers ofdiffering size, i.e., to tailor the diaper to an individual wearer. Suchextension of the waist region or regions may give the absorbent articlea generally hourglass shape, so long as the crotch region is extended toa relatively lesser degree than the waist region or regions, and mayimpart a tailored appearance to the article when it is worn.

As previously mentioned, the diaper pant 100 may include a backsheet136. The backsheet 136 may also define the outer surface 134 of thechassis 102. The backsheet 136 may be impervious to fluids (e.g.,menses, urine, and/or runny feces) and may be manufactured from a thinplastic film, although other flexible liquid impervious materials mayalso be used. The backsheet 136 may prevent the exudates absorbed andcontained in the absorbent core from wetting articles which contact thediaper 100, such as bedsheets, pajamas and undergarments. The backsheet136 may also comprise a woven or nonwoven material, polymeric films suchas thermoplastic films of polyethylene or polypropylene, and/or amulti-layer or composite materials comprising a film and a nonwovenmaterial (e.g., having an inner film layer and an outer nonwoven layer).The backsheet may also comprise an elastomeric film. An examplebacksheet 136 may be a polyethylene film having a thickness of fromabout 0.012 mm (0.5 mils) to about 0.051 mm (2.0 mils). Exemplarypolyethylene films are manufactured by Clopay Corporation of Cincinnati,Ohio, under the designation BR-120 and BR-121 and by Tredegar FilmProducts of Terre Haute, Ind., under the designation XP-39385. Thebacksheet 136 may also be embossed and/or matte-finished to provide amore clothlike appearance. Further, the backsheet 136 may permit vaporsto escape from the absorbent core (i.e., the backsheet is breathable)while still preventing exudates from passing through the backsheet 136.The size of the backsheet 136 may be dictated by the size of theabsorbent core 142 and/or particular configuration or size of the diaper100.

Also described above, the diaper pant 100 may include a topsheet 138.The topsheet 138 may also define all or part of the inner surface 132 ofthe chassis 102. The topsheet 138 may be compliant, soft feeling, andnon-irritating to the wearer's skin. It may be elastically stretchablein one or two directions. Further, the topsheet 138 may be liquidpervious, permitting liquids (e.g., menses, urine, and/or runny feces)to penetrate through its thickness. A topsheet 138 may be manufacturedfrom a wide range of materials such as woven and nonwoven materials;apertured or hydroformed thermoplastic films; apertured nonwovens,porous foams; reticulated foams; reticulated thermoplastic films; andthermoplastic scrims. Woven and nonwoven materials may comprise naturalfibers such as wood or cotton fibers; synthetic fibers such aspolyester, polypropylene, or polyethylene fibers; or combinationsthereof. If the topsheet 138 includes fibers, the fibers may bespunbond, carded, wet-laid, meltblown, hydroentangled, or otherwiseprocessed as is known in the art.

Topsheets 138 may be selected from high loft nonwoven topsheets,apertured film topsheets and apertured nonwoven topsheets. Aperturedfilm topsheets may be pervious to bodily exudates, yet substantiallynon-absorbent, and have a reduced tendency to allow fluids to pass backthrough and rewet the wearer's skin. Exemplary apertured films mayinclude those described in U.S. Pat. Nos. 5,628,097; 5,916,661;6,545,197; and 6,107,539.

As mentioned above, the diaper pant 100 may also include an absorbentassembly 140 that is joined to the chassis 102. As shown in FIG. 2A, theabsorbent assembly 140 may have a laterally extending front edge 148 inthe front waist region 116 and may have a longitudinally opposing andlaterally extending back edge 150 in the back waist region 118. Theabsorbent assembly may have a longitudinally extending right side edge152 and may have a laterally opposing and longitudinally extending leftside edge 154, both absorbent assembly side edges 152 and 154 may extendlongitudinally between the front edge 148 and the back edge 150. Theabsorbent assembly 140 may additionally include one or more absorbentcores 142 or absorbent core layers. The absorbent core 142 may be atleast partially disposed between the topsheet 138 and the backsheet 136and may be formed in various sizes and shapes that are compatible withthe diaper. Exemplary absorbent structures for use as the absorbent coreof the present disclosure are described in U.S. Pat. Nos. 4,610,678;4,673,402; 4,888,231; and 4,834,735.

Some absorbent core embodiments may comprise fluid storage cores thatcontain reduced amounts of cellulosic airfelt material. For instance,such cores may comprise less than about 40%, 30%, 20%, 10%, 5%, or even1% of cellulosic airfelt material. Such a core may comprises primarilyabsorbent gelling material in amounts of at least about 60%, 70%, 80%,85%, 90%, 95%, or even about 100%, where the remainder of the corecomprises a microfiber glue (if applicable). Such cores, microfiberglues, and absorbent gelling materials are described in U.S. Pat. Nos.5,599,335; 5,562,646; 5,669,894; and 6,790,798 as well as U.S. PatentPublication Nos. 2004/0158212 and 2004/0097895.

As previously mentioned, the diaper 100 may also include elasticized legcuffs 156. It is to be appreciated that the leg cuffs 156 can be and aresometimes also referred to as leg bands, side flaps, barrier cuffs,elastic cuffs or gasketing cuffs. The elasticized leg cuffs 156 may beconfigured in various ways to help reduce the leakage of body exudatesin the leg regions. Example leg cuffs 156 may include those described inU.S. Pat. Nos. 3,860,003; 4,909,803; 4,695,278; 4,795,454; 4,704,115;4,909,803; and U.S. patent application Ser. No. 12/434,984.

As mentioned above, diaper pants may be manufactured with a ring-likeelastic belt 104 and provided to consumers in a configuration whereinthe front waist region 116 and the back waist region 118 are connectedto each other as packaged, prior to being applied to the wearer. Assuch, diaper pants may have a continuous perimeter waist opening 110 andcontinuous perimeter leg openings 112 such as shown in FIG. 1.

As previously mentioned, the ring-like elastic belt 104 is defined by afirst elastic belt 106 connected with a second elastic belt 108. Asshown in FIG. 2A, the first elastic belt 106 defines first and secondopposing end regions 106 a, 106 b and a central region 106 c, and thesecond elastic 108 belt defines first and second opposing end regions108 a, 108 b and a central region 108 c.

The central region 106 c of the first elastic belt is connected with thefirst waist region 116 of the chassis 102, and the central region 108 cof the second elastic belt 108 is connected with the second waist region118 of the chassis 102. As shown in FIG. 1, the first end region 106 aof the first elastic belt 106 is connected with the first end region 108a of the second elastic belt 108 at first side seam 178, and the secondend region 106 b of the first elastic belt 106 is connected with thesecond end region 108 b of the second elastic belt 108 at second sideseam 180 to define the ring-like elastic belt 104 as well as the waistopening 110 and leg openings 112.

As shown in FIGS. 2A, 3A, and 3B, the first elastic belt 106 alsodefines an outer lateral edge 107 a and an inner lateral edge 107 b, andthe second elastic belt 108 defines an outer lateral edge 109 a and aninner lateral edge 109 b. The outer lateral edges 107 a, 107 b may alsodefine the front waist edge 120 and the laterally extending back waistedge 122. The first elastic belt and the second elastic belt may alsoeach include an outer, garment facing layer 162 and an inner, wearerfacing layer 164. It is to be appreciated that the first elastic belt106 and the second elastic belt 108 may comprise the same materialsand/or may have the same structure. In some embodiments, the firstelastic belt 106 and the second elastic belt may comprise differentmaterials and/or may have different structures. It should also beappreciated that the first elastic belt 106 and the second elastic belt108 may be constructed from various materials. For example, the firstand second belts may be manufactured from materials such as plasticfilms; apertured plastic films; woven or nonwoven webs of naturalmaterials (e.g., wood or cotton fibers), synthetic fibers (e.g.,polyolefins, polyamides, polyester, polyethylene, or polypropylenefibers) or a combination of natural and/or synthetic fibers; or coatedwoven or nonwoven webs. In some embodiments, the first and secondelastic belts include a nonwoven web of synthetic fibers, and mayinclude a stretchable nonwoven. In other embodiments, the first andsecond elastic belts include an inner hydrophobic, non-stretchablenonwoven material and an outer hydrophobic, non-stretchable nonwovenmaterial.

The first and second elastic belts 106, 108 may also each include beltelastic material interposed between the outer layer 162 and the innerlayer 164. The belt elastic material may include one or more elasticelements such as strands, ribbons, or panels extending along the lengthsof the elastic belts. As shown in FIGS. 2A, 3A, and 3B, the belt elasticmaterial may include a plurality of elastic strands 168 which may bereferred to herein as outer, waist elastics 170 and inner, waistelastics 172. As shown in FIG. 2A, the elastic strands 168 continuouslyextend laterally between the first and second opposing end regions 106a, 106 b of the first elastic belt 106 and between the first and secondopposing end regions 108 a, 108 b of the second elastic belt 108. Insome embodiments, some elastic strands 168 may be configured withdiscontinuities in areas, such as for example, where the first andsecond elastic belts 106, 108 overlap the absorbent assembly 140. Insome embodiments, the elastic strands 168 may be disposed at a constantinterval in the longitudinal direction. In other embodiments, theelastic strands 168 may be disposed at different intervals in thelongitudinal direction. The belt elastic material in a stretchedcondition may be interposed and joined between the uncontracted outerlayer and the uncontracted inner layer. When the belt elastic materialis relaxed, the belt elastic material returns to an unstretchedcondition and contracts the outer layer and the inner layer. The beltelastic material may provide a desired variation of contraction force inthe area of the ring-like elastic belt.

It is to be appreciated that the chassis 102 and elastic belts 106, 108may be configured in different ways other than as depicted in FIG. 2A.For example, FIG. 2B shows a plan view of a diaper pant 100 having thesame components as described above with reference to FIG. 2A, except thefirst laterally extending end edge 144 of the chassis 102 is alignedalong and coincides with the outer lateral edge 107 a of the firstelastic belt 106, and the second laterally extending end edge 146 isaligned along and coincides with the outer lateral edge 109 a of thesecond belt 108.

As previously mentioned, the apparatuses and methods according to thepresent disclosure may be utilized to assemble various components ofpre-fastened, refastenable pant diapers 100. For example, FIG. 4 shows aschematic view of a converting apparatus 300 adapted to manufacture pantdiapers 100. The method of operation of the converting apparatus 300 maydescribed with reference to the various components of pant diapers 100described above and shown in FIGS. 1 and 2A. Although the followingmethods are provided in the context of the diaper 100 shown in FIGS. 1and 2A, it is to be appreciated that various embodiments of diaper pantscan be manufactured according the methods disclosed herein, such as forexample, the absorbent articles disclosed in U.S. Pat. No. 7,569,039,filed on Nov. 10, 2004; U.S. Patent Publication No. 2005/0107764A1,filed on Nov. 10, 2004; U.S. patent application Ser. No. 13/221,127,filed on Aug. 30, 2011; and U.S. patent application Ser. No. 13/221,104,filed on Aug. 30, 2011, which are all hereby incorporated by referenceherein.

As described in more detail below, the converting apparatus 300 shown inFIG. 4 operates to advance discrete chassis 102 along a machinedirection MD such that the lateral axis of each chassis 102 is parallelwith the machine direction, and wherein the chassis 102 are spaced apartfrom each other along the machine direction. Opposing waist regions 116,118 of the spaced apart chassis 102 are then connected with continuouslengths of advancing first and second elastic belt substrates 406, 408.The chassis 102 are then folded along the lateral axis to bring thefirst and second elastic belt substrates 406, 408 into a facingrelationship, and the first and second elastic belt substrates areconnected together along intermittently spaced seams 336. And theelastic belt substrates 406, 408 are cut along the seams 336 to creatediscrete diapers 100, such as shown in FIG. 1.

As shown in FIGS. 4 and 5A, a continuous length of chassis assemblies302 are advanced in a machine direction MD to a carrier apparatus 308and cut into discrete chassis 102 with knife roll 306. The continuouslength of chassis assemblies may include absorbent assemblies 140sandwiched between topsheet material 138 and backsheet material 136, legelastics, barrier leg cuffs and the like. A portion of the chassisassembly is cut-away to show a portion of the topsheet material 138 andan absorbent assembly 140.

After the discrete absorbent chassis 102 are cut by the knife roll 306,the carrier apparatus 308 rotates and advances the discrete chassis 102in the machine direction MD in the orientation shown in FIG. 5B1,wherein the longitudinal axis 124 of the chassis 102 is generallyparallel with the machine direction MD. While the chassis 102 shown inFIG. 5B1 is shown with the first laterally extending end edge 144 as aleading edge and the second laterally extending end edge 146 as thetrailing edge, it is to be appreciated that in other embodiments, thechassis 102 may be advanced in other orientations. For example, thechassis may be oriented such that the first laterally extending end edge144 is a trailing edge and the second laterally extending end edge 146is a leading edge. The carrier apparatus 308 also rotates while at thesame time changing the orientation of the advancing chassis 102. Thecarrier apparatus 308 may also change the speed at which the chassis 102advances in the machine direction MD. It is to be appreciated thatvarious forms of carrier apparatuses may be used with the methodsherein, such as for example, the carrier apparatuses disclosed in U.S.Pat. No. 7,587,966. FIG. 5B2 shows the orientation of the chassis 102 onthe carrier apparatus 308 while advancing in the machine direction. Moreparticularly, FIG. 5B2 shows the chassis 102 with the lateral axis 126of the chassis 102 generally parallel with the machine direction MD, andwherein the first longitudinal side edge 128 is the leading edge and thesecond longitudinal side edge 130 is the trailing edge.

As discussed below with reference to FIGS. 3, 5C, 5D, 5E, and 5F, thechassis 102 are transferred from the carrier apparatus 308 and combinedwith advancing, continuous lengths of belt substrates 406, 408, whichare subsequently cut to form first and second elastic belts 106, 108 ondiapers 100.

With reference to FIGS. 3 and 5C, the chassis 102 are transferred fromthe carrier apparatus 308 to a nip 316 between the carrier apparatus 308and a carrier apparatus 318 where the chassis 102 is combined withcontinuous lengths of advancing front belt 406 and back belt 408substrate material. The front belt substrate material 406 and the backbelt substrate material 408 each define a wearer facing surface 312 andan opposing garment facing surface 314. The wearer facing surface 312 ofthe first belt substrate 406 may be combined with the garment facingsurface 134 of the chassis 102 along the first waist region 116, and thewearer facing surface 312 of the second belt substrate 408 may becombined with the garment facing surface 134 of the chassis 102 alongthe second waist region 118. As shown in FIG. 4, adhesive 320 may beintermittently applied to the wearer facing surface 312 of the first andsecond belt substrates 406, 408 before combining with the discretechassis 102 at the nip 316 between roll 318 and the carrier apparatus308.

With reference to FIGS. 4 and 5D, a continuous length of absorbentarticles 400 are defined by multiple discrete chassis 102 spaced fromeach other along the machine direction MD and connected with each otherby the second belt substrate 408 and the first belt substrate 406. Asshown in FIG. 4, the continuous length of absorbent articles 400advances from the nip 316 to a folding apparatus 500. At the foldingapparatus 500, each chassis 102 is folded in the cross direction CDalong a lateral axis 126 to place the first waist region 116, andspecifically, the inner, body facing surface 132 into a facing, surfaceto surface orientation with the inner, body surface 132 of the secondwaist region 118. The folding of the chassis also positions the wearerfacing surface 312 of the second belt substrate 408 extending betweeneach chassis 102 in a facing relationship with the wearer facing surface312 of the first belt substrate 406 extending between each chassis 102.As shown in FIGS. 4, 5D, and 5E, the folded discrete chassis 102connected with the first and second belt substrates 406, 408 areadvanced from the folding apparatus 500 to a bonder 334. The bonder 334operates to bond a portion of the second belt substrate 408 extendingbetween each chassis 102 with a portion of the first belt substrate 406extending between each chassis 102, thus creating discrete bond regions336. It is to be appreciated that various types of bonder apparatusesand methods can be used to bond the second belt substrate material 408with the first belt substrate material 406, such as for exampledisclosed in U.S. Pat. Nos. 6,248,195; 6,546,987; and 7,383,865, as wellas U.S. patent application Ser. No. 12/795,021, filed Jun. 7, 2010,which are incorporated by reference herein.

As shown in FIGS. 4 and 5F, a continuous length of absorbent articlesare advanced from the bonder 334 to a knife roll 338 where the discretebond regions 336 are cut into along the cross direction to create afirst side seam 178 on an absorbent article 100 and a second side seam180 on a subsequently advancing absorbent article.

As previously mentioned with reference to FIG. 4, the convertingapparatus may include a folding apparatus 500 to fold the chassis 102 ofthe continuous length of absorbent articles 400 in the cross directionCD. FIGS. 6 and 7 show an isometric view of a continuous length ofabsorbent articles 400 advancing in a machine direction MD along anembodiment of a folding apparatus 500. The folding apparatus 500 foldsthe chassis 102 along a folding axis 502 to position the wearer facingsurface 312 of the second belt substrate 408 in a facing relationshipwith the wearer facing surface 312 of the first belt substrate 406. Thefolding apparatus also operates to fold each chassis 102 in the crossdirection CD along the folding axis 502 to place the first waist region116, and specifically, the inner, body facing surface 132 of the firstwaist region 116 into a facing, surface to surface orientation with theinner, body surface 132 of the second waist region 118.

As shown in FIGS. 6, 8, 9, and 10, the folding apparatus 500 may includea conveyor 504 and a plurality of rollers 506. In the convertingarrangement shown in FIG. 6, the conveyor 504 is adapted to advancefirst end portions of the chassis 102, such as the first waist region116, and the first belt material substrate 406 in the machine directionMD along a first web path. And the plurality of rollers 506 is adaptedto advance second end portions of the chassis 102, such as the secondwaist region 118, and the second belt material substrate 408 in themachine direction MD along a second web path. As discussed in moredetail below, each roller 506 may have different angular orientationsrelative to another to provide a substantially helical shape to thesecond path along the machine direction MD. It is to be appreciated thatthe folding apparatus may include various other arrangements ofcomponents than those described and shown in herein. For example, someembodiments of the folding apparatus may include a plurality of rollersinstead of a conveyor 504, and may include a twisted belt conveyorarrangement instead of a plurality of rollers 506.

As previously mentioned, the folding apparatus 500 may include conveyor504 and the plurality of rollers 506. For example, the conveyor 504 ofthe folding apparatus 500 shown in FIGS. 6, 8, 9, and 10 includes a belt514 that advances the first belt material substrate 406 and first waistregions 116 of the chassis 102 along the first web path. The foldingapparatus 500 also includes ten rollers 506, labeled as 506 a through506 j, that advance the second belt material substrate 408 and secondwaist regions 118 of the chassis 102 along the second web path. Eachroller 506 defines a rotation axis 508 (labeled 508 a through 508 j). Asdiscussed in more detail below, the rotation axis of a roller 506 may beangularly offset relative to a preceding roller 506 upstream in themachine direction MD. As the second belt material substrate 408 andsecond waist regions 118 of the chassis 102 advance along the second webpath, the relative angular positions between the rollers 506 cause thesecond belt material substrate 408 and second waist regions 118 of thechassis 102 to twist while advancing in the machine direction MD, and atthe same time, fold the chassis 102 along the folding axis 502 to placethe second belt substrate 408 into a facing relationship with the firstbelt substrate 406. The folding axis 502 may also be defined by an arcextending in the machine direction MD, wherein second belt materialsubstrate 408 and second end region of the chassis are helically foldedtoward the inside of the arc. As discussed in more detail below, thecurved or arc-shaped folding axis may be configured such the first andsecond web paths have substantially equal lengths.

With continued reference to FIG. 6, an x-y-z axis coordinate system 510is provided to help provide additional reference to the description ofthe folding apparatus 500. As shown in FIG. 6, the first belt materialsubstrate 406, second belt material substrate 408, and chassis 102advance toward rollers 512 along the machine direction MD in the +xdirection, with a cross direction CD along the ±y direction. Afterpassing the rollers 512, the first belt material substrate 406, secondbelt material substrate 408, and chassis 102 advance toward the foldingapparatus 500 along the machine direction MD in the +z direction, with across direction CD along the ±y direction. More particularly, the firstbelt material substrate 406 and first waist regions 116 of the chassis102 advance from the roller 512 in the +z direction to the belt 514 ofthe folding apparatus 500, and the second belt material substrate 408and second waist regions 118 of the chassis 102 advance from the roller512 in the +z direction to the first roller 506 a of the foldingapparatus 500. As such, before engaging the folding apparatus 500, thefirst belt material substrate 406, second belt material substrate 408,and chassis 102 advance in the machine direction MD along asubstantially two-dimensional plane (e.g. x-y plane or y-z plane).

Upon engaging the folding apparatus 500, the conveyor 504 advances thefirst belt material substrate 406 and first waist regions 116 of thechassis 102 in the machine direction MD along the first web path. Asshown in FIGS. 6, 8, and 10, the conveyor defines a curved path having+z and +x directional components along the MD direction. It is to beappreciated that various type of conveyor arrangements may be used. Forexample, as shown in FIG. 10, the conveyor 504 may include an endlessbelt 514 supported by a plurality of rollers 516. The endless belt 514may define a carrier surface 518 that contacts the wearer facing surface312 of the first belt substrate 406 and/or the inner, body facingsurface 132 of the first waist region 116 of the chassis 102.

As the first belt material substrate 406 and first waist regions 116 ofthe chassis 102 advance along the conveyor 504, the second belt materialsubstrate 408 and second waist regions 118 of the chassis 102 advancealong the second web path defined by the rollers 506. In particular, thesecond path defined by the rollers 506 guides and/or advances the secondbelt material substrate 408 and second waist regions 118 of the chassis102 to fold the chassis 102 along the folding axis 502. At the sametime, the rollers 506 advance the second belt material substrate 408 andsecond waist regions 118 of the chassis 102 in the machine direction andinto a facing relationship with the first belt material substrate 406and first waist regions 116 of the chassis 102. As discussed in moredetail below, the folding axis 502 may be located in a cross directionalposition between the conveyor 504 and the rollers 506 in the upstreammachine direction MD region of the folding apparatus. In addition, thefolding axis 502 may be curved along the machine direction. For example,the folding axis 502 shown in FIGS. 6, 8, 9, and 11 defines a curvedpath having +z and +x directional components along the MD direction.

As previous mentioned, the folding apparatus may include a plurality ofrollers 506 that define the second web path. For example, the foldingapparatus 500 of FIGS. 6, 8, 9, and 11, includes ten rollers 506 a-506 jspaced from each other along the machine direction MD. Five rollers 506a-506 e in the upstream machine direction MD of the folding apparatus500 contact the wearer facing surface 312 of the second belt substrate408, and five rollers 506 f-506 j in the downstream machine direction MDof the folding apparatus 500 contact the garment facing surface 314 ofthe second belt substrate 408. Each roller 506 a-506 j also defines arotation axis 508 a-508 j, respectively.

As mentioned above, the rotation axis 508 a-508 j of each roller 506a-506 j may be angularly offset relative to the rotation axis of apreceding roller upstream in the machine direction MD. One exampleconfiguration of the aforementioned angular offset may described withreference to FIGS. 6, 8, 11, and 11 a and the illustrated x-y-zcoordinates 510, and in particular, may be described based on anglesdefined between each rotation axis 508 a-508 j and the +y axis. Asshown, the first rotation axis 508 a is aligned with the +y axis, and assuch, a first angle, θ1, defined between the rotation axis 508 a of thefirst roller 506 a the +y axis is 0°. The second rotation axis 508 b ofthe second roller 506 b is angularly offset from the first rotation axis508 a, and as such, a second angle, θ2, defined between the secondrotation axis 508 b and the +y axis is greater than the first angle, θ1.The third rotation axis 508 c of the third roller 506 c is angularlyoffset from the second rotation axis 508 b, and as such, a third angle,θ3, defined between the third rotation axis 508 c and the +y axis isgreater than the second angle, θ2. The fourth rotation axis 508 d of thefourth roller 506 d is angularly offset from the third rotation axis 508c, and as such, a fourth angle, θ4, defined between the fourth rotationaxis 508 d and the +y axis is greater than the third angle, θ3. Thefifth rotation axis 508 e of the fifth roller 506 e is angularly offsetfrom the fourth rotation axis 508 d, and as such, a fifth angle, θ5,defined between the fifth rotation axis 508 e and the +y axis is greaterthan the fourth angle, θ4.

In the arrangement shown in FIGS. 6, 8, 11, and 11 a, the sixth rotationaxis 508 f of the sixth roller 506 f is not angularly offset from thefifth rotation axis 508 e, and as such, a sixth angle, θ6, definedbetween the sixth rotation axis 508 f and the +y axis is the same as thefifth angle, θ5. The seventh rotation axis 508 g of the seventh roller506 g is angularly offset from the sixth rotation axis 508 f, and assuch, a seventh angle, θ7, defined between the seventh rotation axis 508g and the +y axis is greater than the sixth angle, θ6. The eighthrotation axis 508 h of the eighth roller 506 h is angularly offset fromthe seventh rotation axis 508 g, and as such, an eighth angle, θ8,defined between the eighth rotation axis 508 h and the +y axis isgreater than the seventh angle, θ7. The ninth rotation axis 508 i of theninth roller 506 i is angularly offset from the eighth rotation axis 508h, and as such, a ninth angle, θ9, defined between the ninth rotationaxis 508 i and the +y axis is greater than the eighth angle, θ8. Thetenth rotation axis 508 j of the tenth roller 506 j is angularly offsetfrom the ninth rotation axis 508 i, and as such, a tenth angle, θ10,defined between the tenth rotation axis 508 j and the +y axis is greaterthan the ninth angle, θ9.

It is to be appreciated that various embodiments of the foldingapparatus 500 may include various quantities of rollers 506 angularlyoffset from each other in various ways. For example, Table 1 below showsone embodiment of an angular offset arrangement of the rollers 506 shownin FIGS. 6, 11, and 11 a.

TABLE 1 Angle Between Relative Angular Offset Rotation Rotation Axiswith Respect to Roller Axis and +y Axis Upstream Rotation Axis 506a 508a θ1 = 0° 506b 508b  θ2 = 22.5° 22.5° 506c 508c  θ3 = 45° 22.5° 506d 508d θ4 = 67.5° 22.5° 506e 508e  θ5 = 90° 22.5° 506f 508f  θ6 = 90°    0°506g 508g  θ7 = 112.5° 22.5° 506h 508h  θ8 = 135° 22.5° 506i 508i  θ9 =157.5° 22.5° 506j 508j θ10 = 180° 22.5°

As shown in the FIGS. 6, 8, 9, and 11, the folding axis 502 may bedefined by a rail 520 around which the crotch region 120 of theadvancing chassis 102 may be folded. As previously mentioned, thefolding axis 302 extends in the machine direction and may be curved. Forexample, the curved folding axis 502 shown in FIGS. 6, 8, 9, and 11defines has both +z and +x directional components along the MDdirection. It is to be appreciated that the folding axis 502 may bedefined in various ways and may extend in various lengths along themachine direction MD. In some embodiments, the folding axis 502 may bedefined by a continuous arc. In other embodiments, the folding axis 502may be defined by a plurality of arcs of different radii. In yet otherembodiments, the folding axis 502 may be defined by one or more arcs incombination with one or more straight portions. In some embodiments, thefolding axis 502 may include straight segments connected arcuatesegments. In some embodiments, such straight segments may approximate achord of the ideal folding rail arc between successive folding segments.It is also to be appreciated that in some embodiments, the folding axis502 may be defined by an edge of conveyor 504.

FIG. 12 shows an example of a folding axis 502, which may also bedefined by a rail 520. The folding axis 502 in FIG. 12 is defined bynine segments 601-609. More particularly, the folding axis 502 extendsin the machine direction MD from a first segment 601 to a ninth segment609 along a curved path having +x and +z components. More particularly,the folding axis 502 extends in the machine direction MD from a firstsegment 601 extending between a first end portion 601 a and a second endportion 601 b; to a second segment 602 extending between a first endportion 602 a and a second end portion 602 b; to a third segment 603extending between a first end portion 603 a and a second end portion 603b; to a fourth segment 604 extending between a first end portion 604 aand a second end portion 604 b; to a fifth segment 605 extending betweena first end portion 605 a and a second end portion 605 b; to a sixthsegment 606 extending between a first end portion 606 a and a second endportion 606 b; to a seventh segment 607 extending between a first endportion 607 a and a second end portion 607 b; to an eighth segment 608extending between a first end portion 608 a and a second end portion 608b; and to a ninth segment 609 extending between a first end portion 609a and a second end portion 609 b.

It is to be appreciated that some segments 601-609 of the folding axis502 may have the same or different lengths; may be straight; and may becurved, wherein such curves may be defined by the same or differentradii R1-R9. For example, Table 2 below shows the relative lengths asdefined by various radii extending along various arc angles.

TABLE 2 Segment Radius Arc Angle 601 R1 = 1.1 meters 17°  602 R2 = 2.9meters 6° 603 R3 = 4.3 meters 4° 604 R4 = 6.7 meters 3° 605 R5 = seenote below See note below 606 R6 = 6.7 meters 3° 607 R7 = 4.3 meters 4°608 R8 = 2.9 meters 6° 609 R9 = 1.1 meters 17°  Note: In the embodimentof Table 2, the fifth segment 605 is a straight 25 mm length.

As previously mentioned, it is to be appreciated that variousembodiments of the folding apparatus 500 may include various quantitiesof rollers 506 angularly offset from each other in various ways. Forexample, FIG. 13 shows another embodiment of a folding apparatusincluding eight rollers 506. Consistent with the description providedabove with reference to Table 1 and associated FIGS. 11, 11 a, and 12,Table 3 below shows one embodiment of an angular offset arrangement ofthe rollers 506 shown in FIG. 13.

TABLE 3 Angle Between Relative Angular Offset Rotation Rotation Axiswith Respect to Roller Axis and +y Axis Upstream Rotation Axis 506a 508aθ1 = 0° 506b 508b θ2 = 36° 36° 506c 508c θ3 = 70° 34° 506d 508d θ4 = 74° 4° 506e 508e θ5 = 105° 32° 506f 508f θ6 = 110°  4° 506g 508g θ7 = 144°34° 506h 508h θ8 = 180° 36°

FIG. 13 also shows an example of a folding axis 502, which may also bedefined by a rail 520 similarly described above with reference to FIGS.11, 11 a, and 12. As shown in FIG. 13, the folding axis 502 may bedefined by seven segments 601-607, and Table 4 below shows examples ofrelative lengths of the segments as defined by various radii extendingalong various arc angles.

TABLE 4 Segment Radius Arc Angle 601 R1 = 1.9 meters 17.5°  602 R2 = 5.6meters 5.9° 603 R3 = 8.0 meters 0.5° 604 R4 = 7.5 meters 4.2° 605 R5 =8.0 meters 0.5° 606 R6 = 5.0 meters 6.0° 607 R7 = 1.9 meters 15.4° 

As discussed above with regard to the folding processes herein, thefirst end region of the advancing substrate travels in the machinedirection along a first web path during the folding process while thesecond end region of the substrate travels in the machine directionalong a second web path defining a helical shape. The folding axis mayalso be defined by an arc extending in the machine direction MD, whereinthe second end region of the advancing substrate is helically foldedtoward the inside of the arc. Further, the folding apparatus including acurved or arc-shaped folding axis may be configured such the first andsecond web paths have substantially equal lengths.

In some embodiments, the length of the first web path may be defined bythe travel path of substrate 406 as the substrate 406 advances along theconveyor 504 from the first end position 601 a to the second endposition 609 b of the folding axis 502. And the length of the second webpath may be defined by the travel path of the substrate 408 as thesubstrate 408 advances in the machine direction along rollers 506 athrough 506 j. For each segment between consecutive rollers 506, thelength of the second web path may be calculated by solving for athree-dimensional distance between contact points of substrate 408against the rollers 506 given an assumed arc distance along the curvedfolding axis 502 and an assumed relative angular offset betweenconsecutive rollers 506 a through 506 j. The distance between contactpoints of substrate 408 at the edge closest to folding axis 502 may besolved to be equal to the distance between the contact points ofsubstrate 408 at the edge farthest from folding axis 502 by varying theangle between the rotation axis and the +y-axis, as shown in Table 2above.

It is to be appreciated that the apparatuses and methods herein may beconfigured to provide for relatively low web strains and maintainrelatively flat webs during the folding process. In some embodiments,the web strain of the outboard edge of the second web path may thereforethe same as the web strain of a continuous web along the folding axis502. In some embodiments, the rollers may be slightly displaced from theinitial positions to help improve traction of substrate 408 on therollers 506, and to help maintain substrate 408 substantially in contactwith each roller along the cross machine direction. The helical pathsubstantially defines the contact points of the substrate 408, and therollers may be displaced on either surface of substrate 408. With aknown distance between consecutive rollers 506, known rotation angle ofeach roller 506, the second web path may be fully defined. In such aninitial condition, the web strain in web path 408 may substantiallymatch the design strain at folding axis 502. In some embodiments, thedesign strain may be within a range of 0.5% to 2.0% machine direction(MD) strain, and may be 1.25% MD strain. Such a condition may exist forthe inboard and outboard portions of the second substrate 408. In thecenter of substrate 408, the web strain may be as low as 0.1%. In someinstances, a slight offset of the rotational angle may be sufficient tobalance the MD strain of the inboard edge of substrate 408 and theoutboard edge of substrate 408. In some embodiments, values for the MDstrain at the inboard edge of substrate 408 may be 0.1% to 0.3%. Inother embodiments, values for the MD strain at the inboard edge ofsubstrate 408 may be 0.5%, and in some instances, as high as 1.25% tomatch the MD strain at the folding axis 502. In some embodiments, the MDstrain at the center of substrate 408 may be about 0.2%.

It is to be appreciated that various embodiments of methods andapparatus may include varying fold angles between adjacent rollers,angles of folding axis between adjacent rollers, and span lengthsbetween adjacent rollers. It is also to be appreciated that the patternof idlers in the folding apparatus may vary substantially. Solutions ofidler angle of rotation in a plane normal to the folding axis andcurvature of the helical path may exist for any span length. Embodimentswith small angular rotation of the fold between spans and short spansmay be possible, as embodiments with large rotations of the folding webaround the fold axis, with corresponding larger span lengths. Straightsegments with nominally no folding may be added at any point in thefold, and may be added at the midpoint of the fold, to allow consecutiverollers to contact alternate sides of the web.

In some embodiments, the apparatus may be configured to exert and/ormaintain cross direction tension on the substrate. For example, in someembodiments, folding apparatus may be configured such that the outboardedge of the substrate has a longer path length than the opposingoutboard edge. In some configurations, the path length may be 0.5 to 2%longer. In yet another example, the apparatus may be configured withtapered rollers having relatively larger diameters near the outboardedge of the substrate and relatively smaller diameters near the foldline of the substrate. In yet other configurations, the apparatus mayinclude skewed rollers, such that the axis of revolution of each rolleris not in a plane normal to the fold axis. It is also to be appreciatedthat other devices may be used to provide a web spreading function,including for example, static bars, folding plows, curved static barssuch as bow or banana bars, elastomeric idlers including those withdeformable spreading surfaces such as an Arco roller from AmericanRoller, Inc., Mt. Hope rolls, and many other devices. Such spreadingdevices may comprise the folding rollers or may be additional to thefolding rollers.

In some embodiments, the folding apparatus may include an arrangementfor anchoring the non-folded side of the substrate. More particularly,an anchoring mechanism may be used such that the folding side of the webcan be pulled in a cross directional direction via an arrangement ofcomponents touching the web, such as rollers, folding plows, drivenrollers or the like, while the non-folded side is transported withoutfolding and with little or no change of position in the cross-machinedirection. In some embodiments, the anchoring mechanism may include avacuum conveyor, which may also include a pitched belt such that vacuumholes are primarily under impermeable film sections of the substratebeing folded. In yet other embodiments, the anchoring mechanism mayoperate to compress of the substrate between opposing belts or rollers.In some embodiments, the compression or vacuum used to control thesubstrate may occur primarily at the crotch region. In some embodiments,spring loaded rollers, pneumatically engaged rollers, pneumatic tires,internally pressurized elastomeric elements, elastomeric rollers,elastomeric rollers with internal voids may be used to control the pad.

In some embodiments of the folding apparatus, the line of contact of thesubstrate at each folding roller may be tangent to the outboard surfaceof the folding rail. The solution of sequential cross-sections of theweb as it revolves around the folding axis describes the position of thearticle which is being folded. The rollers which contact the article maybe on either the inside or outside of the web. It may also be possibleto displace idlers from the ideal tangent solution to increase wrapangle on roller elements. In some embodiments, rollers are displacedfrom the ideal tangent contact, equal strain solution to ensure the webhas a non-zero contact length with each roller element. Displacement ofidlers may be in the Y or Z direction. In some embodiments, rollers atclosely spaced pairs with alternating contact sides may be displaced toensure full width contact. In some embodiments, the last, horizontal,roller is displaced to avoid interference with a folding rail orconveyor.

In some embodiments, the folding apparatus is followed by a waistalignment unit, that may include upper and/or lower vacuum conveyors.Such conveyors may pivot to provide a web steering function to alignfeatures of the folded and non-folded sides of the article, eitherrelative to each other or relative to a reference value. Detection ofthe tracking position may be by dedicated sensor or a machine visionsystem. In some embodiments, edges of a waist belt on the folded sideand the non-folded side of an article are detected using an FR6001sensor commercially available from Erhardt+Leimer. In some embodiments,these sensors are mounted on a singled fixed bracket, and setpointadjustments are made by changing a variable in the electroniccontroller. In some embodiments, the waist alignment unit may bereplaced by a tracking device at one of the folding board rollers, whichmay include a camber roller replacing one or more of the folding rollers506 a-j. Such a camber roller may also be feedback controlled via adownstream sensor or vision system.

To maintain machine direction alignment of the folding and non-foldingportions of the substrate, one of more elements of the drive system mayhave a controllable velocity. In some embodiment, the speed of adownstream drive point, preferably a vacuum conveyor may be varied,while maintaining the folding conveyor and a downstream drive point forthe non-folded side at a constant surface velocity. Such velocitycontrol may be open loop, but may also be accomplished by closed loopfeedback control based upon signals from downstream sensors or machinevision systems. An example of such a feedback control system is aProportional-Integral-Derivative (PID) controller, optionally withfeed-forward and speed compensation, such as is implemented in commonindustrial controllers, such as the ControLogix platform from RockwellAutomation. The input signal may also include a position offset betweenfolded and unfolded features on one or a series of articles. The inputsignal may also be a time difference measured between features on foldedand unfolded portions of one or a series of articles. It is also to beappreciated that the machine direction alignment of features on foldedand unfolded portions of one or a series of articles may also beaccomplished by varying the path length of either the folded or unfoldedportion of the substrate.

In some embodiments, the substrate may be delivered flat at the infeedof the folding system. In some embodiments, opposed pivoting camberrollers track and spread the web prior to folding. In some embodiments,the tracking function and spreading functions are feed-back controlled,using commercially available web guides. In some embodiments, thesensors of these web guides may be connected to a quality monitoringsystem, the edge positions of each side of the web may be stored, and/orthe setpoints and control parameters may be remotely adjusted through anelectronic controller. The folding centerline may be set by thecross-machine direction position of the substrate as the substrateenters the folder.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A method of folding a continuous length ofabsorbent articles comprising a plurality of intermittently spacedchassis advancing in a machine direction, each chassis having a firstend portion and an opposing second end portion separated from each otherin a cross direction by a central portion, and each chassis having afirst surface and an opposing second surface, the method comprising thesteps of: providing a rail comprising curved segments; advancing thefirst end portions of the chassis in the machine direction on a firstweb path; advancing the second end portions of the chassis in themachine direction on a second web path to fold the second end portionsof the chassis 180° around the curved segments of the rail to positionthe second surfaces of the second end portions of the chassis into afacing relationship with the second surfaces of the first end portionsof the chassis as the chassis advance in machine direction; andadvancing the central portions of the chassis in the machine directionon the curved segments of the rail while folding the second endportions, wherein the central portion of each chassis is advanced alongthe curved segments of the rail simultaneously as the second end portionof the chassis is folded 180° around the curved segments of the rail toposition the second surface of the second end portion of the chassisinto a facing relationship with the second surface of the first endportion of the chassis, wherein a plurality of the curved segments ofthe rail are defined by different radii such that the second web pathand the first web path comprise substantially equal lengths.
 2. Themethod of claim 1, wherein the rail comprises nine curved segmentshaving five different lengths.
 3. The method of claim 1, wherein therail further comprises a straight segment positioned between two curvedsegments.
 4. The method of claim 1, wherein the rail comprises sevencurved segments having five different lengths.